The present invention relates to a transfer sheet for an adhesive layer, particularly a transfer sheet, for an adhesive layer, which has a combination of excellent adhesion to a transfer material and excellent adhesion to an image-forming object or releasability of an adhesive layer from the transfer sheet for an adhesive layer, and an image-forming method and an object, with an image formed thereon, using the transfer sheet for an adhesive layer.
Further, the present invention relates to a transfer sheet for an adhesive layer, particularly a transfer sheet, for an adhesive layer, which can conduct temporary bonding and separation a plurality of times in bonding a transfer material to a different material through an adhesive layer transferred onto the transfer material, an image-forming method using the transfer sheet for an adhesive layer, and an object, with an image formed thereon, and, an intermediate thereof, that is, an intermediate image-forming object, formed using the transfer sheet for an adhesive layer.
A melt type thermal transfer system and a sublimation type thermal transfer system have hitherto been used extensively as a thermal transfer system. In the sublimation type thermal transfer system, a thermal transfer sheet comprising a substrate sheet, such as a plastic film, bearing a dye layer formed of a binder resin with a sublimable dye as a colorant melted or dispersed therein is used with an image-forming object comprising a support, such as paper or a plastic sheet, bearing an image-receptive layer, and energy corresponding to image information is applied by means of a heating device, such as a thermal head, to transfer a sublimable dye contained in a dye layer of the thermal transfer sheet onto an image-receptive layer of the image-forming object, thereby recording an image. According to the sublimation type thermal transfer system, the amount of the dye transferred can be regulated on a dot basis by regulating the amount of energy applied to the thermal transfer sheet, enabling tone reproduction by taking advantage of density gradation. Further, since the colorant used is a dye, the recorded image has good transparency and, at the same time, the reproduction of an intermediate color created by superposition of colors using a plurality of dye layers is excellent. Therefore, a high-quality, full-color image can be recorded by using a thermal transfer sheet(s) for three colors of yellow, magenta, and cyan or four colors of yellow, magenta, cyan, and black to superpose these three or four colors on top of one another on an object.
In the formation of an image by the sublimation type thermal transfer system, an image can be formed on image-forming materials having various shapes by once forming an image on an intermediate transfer medium having an image-receptive layer and transferring the image-receptive layer, with an image formed thereon, onto an image-forming object. The formation of an image using the intermediate transfer medium by the sublimation type thermal transfer system, however, often suffers from a drawback that the adhesion between the image-receptive layer and the image-forming object in its image-forming surface is unsatisfactory. In this case, it is preferred to transfer the image-receptive layer onto the image-forming object through an adhesive layer.
According to the present invention, a transfer sheet for an adhesive layer is used in the formation of an adhesive layer used in the above transfer of an image-receptive layer onto an image-forming object. Specifically, the transfer sheet, for an adhesive layer, according to the present invention basically comprises a substrate sheet and an adhesive layer provided on the substrate sheet. It is put on top of an image-receptive layer in an intermediate transfer medium so as for the adhesive layer to face the image-receptive layer, and, in this state, heat and pressure are applied through the substrate sheet to transfer the adhesive layer onto the image-receptive layer in the intermediate transfer medium.
The transferred adhesive layer is in direct contact with the image-receptive layer in the intermediate transfer medium. Therefore, the adhesive layer should be formed of a resin that has good adhesion to the resin constituting the image-receptive layer and into which the dye constituting the image is not bled. This greatly limits the material usable for the adhesive layer. Further, an adhesive layer, that is easily adhered to the image-receptive layer, is in many cases difficult to be adhered to an image-forming object, such as paper. In this respect as well, there is a limitation on the selection of the material. Furthermore, when the image-forming object is one having a fiber texture, such as paper, the transfer of an image-receptive layer onto an image-forming object through an adhesive layer causes the adhesive layer to be penetrated into the image-forming object, posing a problem that the fiber texture of the image-forming object appears on the surface of the formed image.
Good releasability of the adhesive layer from the substrate sheet is required of the thermal transfer sheet for an adhesive layer. If the transferred adhesive layer has a smaller thickness than a desired one or poor surface smoothness, the adhesion of the transferred image-receptive layer to an image-forming object is poor, or irregularities are created on the image-receptive layer, resulting in deteriorated image quality.
Further, when the image-receptive layer with an adhesive layer formed thereon by transfer is transferred onto an image-forming object through the adhesive layer, or when an image-receptive layer is transferred onto an image-forming object, with an adhesive layer formed thereon by transfer, through the adhesive layer, registration is necessary between the image-receptive layer and the image-forming object. In the case of an adhesive layer formed by transfer using the transfer sheet for an adhesive layer, when the image-receptive layer or the image-forming object once comes into contact with and adhered to the adhesive layer of the transfer sheet for an adhesive layer, there is a possibility that the adhesive layer cannot be separated from the sheet, making it impossible to release and again adhere the adhesive layer for more accurate registration. For this reason, registration while repeating contact and separation between the image-receptive layer and the image-forming object a plurality of times becomes impossible, imposing restriction on registration work at the time of transfer of the image-receptive layer onto the image-forming object.
In view of the above situation, the present invention has been made, and an object of the present invention is to provide a transfer sheet, for an adhesive layer, which can transfer an adhesive layer and has excellent adhesion to a transfer material (an intermediate transfer medium), is free from bleeding of dyes, has excellent adhesion to an image-forming object, and is free from penetration into the image-forming object, and an image-forming method and an object, with an image formed thereon, using said transfer sheet for an adhesive layer.
Another object of the present invention is to provide a transfer sheet, for an adhesive layer, which can transfer and form an adhesive layer, with desired thickness, possessing very good releasability and having uniform thickness and high surface smoothness.
A further object of the present invention is to provide a transfer sheet, for an adhesive layer, which is excellent in transferability and adhesion of an adhesive layer onto a transfer material and enables temporary bonding and separation to be repeated a plurality of times to achieve satisfactory positioning for bonding of a transfer material to a different object, an image-forming method, which can form a high-quality image using said transfer sheet for an adhesive layer, and an object, with an image formed thereon, and an intermediate thereof, that is, an intermediate image-forming object, formed using the transfer sheet for an adhesive layer.
The transfer sheet for an adhesive layer according to the present invention basically comprises a substrate sheet and an adhesive layer separably provided on the substrate sheet.
Further, it embraces transfer sheets, for an adhesive layer, improved for solving the above technical problems.
Thus, according to one aspect of the present invention, there is provided a transfer sheet for an adhesive layer, comprising: a substrate sheet; and an adhesive layer and an interposing layer laminated in that order on at least part of one surface of the substrate sheet, the substrate sheet and the adhesive layer being separable from each other.
According to a preferred embodiment of the present invention, the interposing layer has a glass transition point in the range of from 50 to 115xc2x0 C. and the adhesive layer has a glass transition point in the range of from 35 to 100xc2x0 C., the glass transition point of the interposing layer being above that of the adhesive layer; at least one of the interposing layer and the adhesive layer contains a filler; or the transfer sheet for an adhesive layer further comprises a back surface layer on the surface of the substrate sheet remote from the adhesive layer.
According to another aspect of the present invention, there is provided an image forming method comprising the steps of: forming an image on a releasable image-receptive layer in an intermediate transfer medium by a thermal sublimation transfer process; putting the intermediate transfer medium and the above transfer sheet, for an adhesive layer, on top of the other so as for the image-receptive layer to abut against the interposing layer on the intermediate transfer medium and applying heat and/or pressure to the laminate by transfer means to transfer the adhesive layer onto the image-receiving layer through the interposing layer; and putting an image-forming object onto the intermediate transfer medium so as for the image-forming object to abut against the adhesive layer and applying heat and/or pressure to the laminate by transfer means to transfer the image-receptive layer onto the image-forming object through the adhesive layer.
According to a further aspect of the present invention, there is provided an object with an image formed thereon, comprising: an image-forming object; an adhesive layer and an interposing layer laminated in that order on a desired site of the image-receiving object; and an image-receptive layer provided on the interposing layer, the image-receptive layer having an image formed by a thermal sublimation transfer process.
According to a preferred embodiment of the present invention, in the object with an image formed thereon, the interposing layer has a glass transition point in the range of from 50 to 115xc2x0 C. and the adhesive layer has a glass transition point in the range of from 35 to 100xc2x0 C., the glass transition point of the interposing layer being above that of the adhesive layer; or at least one of the interposing layer and the adhesive layer contains a filler.
The adhesive layer provided on the substrate sheet has thereon an interposing layer which has good adhesion to a transfer material, onto which the adhesive layer is to be transferred, and, at the same time, can prevent bleeding of dyes. Therefore, the transfer of the adhesive layer onto a transfer material is very good, and, for the adhesive layer, importance can be placed on the adhesion to the image-forming object and properties which enable prevention of penetration of the adhesive layer, thus realizing a transfer sheet, for an adhesive layer, which can develop good transfer onto a transfer material by virtue of the interposing layer and good transfer onto an image-forming object by virtue of the adhesive layer.
According to a further aspect of the present invention, there is provided a transfer sheet for an adhesive layer, comprising: a substrate sheet; and a peel layer and an adhesive layer laminated in that order on at least part of one surface of the substrate sheet, the substrate sheet and the peel layer being separable from each other, the glass transition point of the peel layer being above that of the adhesive layer.
In a preferred embodiment of the present invention, the peel layer has a glass transition point in the range of from 50 to 115xc2x0 C. and the adhesive layer has a glass transition point in the range of from 35 to 100xc2x0 C.; at least one of the peel layer and the adhesive layer contains a filler; or the transfer sheet for an adhesive layer further comprises a back surface layer on the surface of the substrate sheet remote from the adhesive layer.
According to a yet further aspect of the present invention, there is provided an image-forming method comprising the steps of: forming an image on a releasable image-receptive layer in an intermediate transfer medium by a thermal sublimation transfer process; putting an image-forming object and a transfer sheet for an adhesive layer according to any one of the above thermal transfer sheets, for an adhesive layer, on top of the other so as for the adhesive layer of the transfer sheet for an adhesive layer to abut against the image-forming object and applying heat and/or pressure to the laminate by transfer means to transfer the adhesive layer, together with the peel layer, onto the image-forming object; and putting the image-forming object and the intermediate transfer medium on top of the other so as for the peel layer to abut against the image-receptive layer and applying heat and/or pressure to the laminate by transfer means to transfer the image-receptive layer onto the image-forming object through the peel layer and the adhesive layer.
According to a yet further aspect of the present invention, there is provided an object with an image formed thereon, comprising: an image-forming object; an adhesive layer and a peel layer laminated in that order on a desired site of the image-forming object, the glass transition point of the peel layer being above that of the adhesive layer; and an image-receptive layer provided on the peel layer, the image-receptive layer having thereon an image formed by a thermal sublimation transfer process.
According to a preferred embodiment of the present invention, the peel layer has a glass transition point in the range of from 50 to 115xc2x0 C. and the adhesive layer has a glass transition point in the range of from 35 to 70xc2x0 C.; or at least one of the peel layer and the adhesive layer contains a filler.
In the object with an image formed thereon, an adhesive layer is provided on a substrate sheet through a peel layer, and the peel layer has a glass transition point above the adhesive layer. By virtue of this construction, in the transfer of the adhesive layer, good separation occurs between the substrate sheet and the peel layer, eliminating the need for the adhesive layer to have releasability from the substrate sheet. This enables the adhesive layer to have high adhesion to a transfer material. Further, since the peel layer is located on the surface of the transferred adhesive layer, good surface properties can be maintained even though the adhesive layer penetrates into the transfer material.
According to a yet further aspect of the present invention, there is provided a transfer sheet for an adhesive layer, comprising: a substrate sheet; and a release layer and an adhesive layer laminated in that order on at least part of one surface of the substrate sheet, the release layer and the adhesive layer being separable from each other.
In a preferred embodiment of the present invention, the release layer contains a release agent; the release agent is a silicone compound; the adhesive layer is a laminate of two or more adhesive layers; and/or the thermal transfer sheet further comprises a back surface layer on the surface of the substrate sheet remote from the adhesive layer.
The adhesive layer is provided on the substrate sheet through a release layer. The release layer functions to suitably hold the adhesive layer and, at the same time, exhibits good releasability from the adhesive layer at the time of transfer without deteriorating the adhesive property of the adhesive layer, resulting in transfer of the adhesive layer in uniform thickness without leaving any residue of the adhesive layer on the substrate sheet side.
According to a yet further aspect of the present invention, there is provided a transfer sheet for an adhesive layer, comprising: a substrate sheet; and a releasable adhesive layer having low tackiness provided on at least part of one surface of the substrate sheet.
In a preferred embodiment of the present invention, the transfer sheet for an adhesive layer further comprises an interposing layer on the adhesive layer; at least one of the adhesive layer and the interposing layer contains a filler; a peel layer is provided between the substrate sheet and the adhesive layer, the peel layer and the substrate sheet being separable from each other; the glass transition point of the peel layer is above that of the adhesive layer; or the transfer sheet for an adhesive layer further comprises a back surface layer on the surface of the substrate sheet remote from the adhesive layer.
According to a yet further aspect of the present invention, there is provided an image forming method comprising the steps of: forming an image on a releasable image-receptive layer in an intermediate transfer medium by a thermal sublimation transfer process; putting the intermediate transfer medium and a transfer sheet for an adhesive layer according to any one of the transfer sheets, for an adhesive layer, on top of the other so as for the image-receptive layer to abut against the adhesive layer or the interposing layer of the transfer sheet for an adhesive layer and applying heat and/or pressure to the laminate by transfer means to transfer the adhesive layer onto the image-receptive layer; putting the intermediate transfer medium and an image-forming object on top of the other for registration by taking advantage of the low tackiness of the adhesive layer present on the intermediate transfer medium; and transferring the image-receptive layer onto the image-forming object through the adhesive layer.
According to a yet further aspect of the present invention, there is provided an image forming method comprising the steps of: forming an image on a releasable image-receptive layer in an intermediate transfer medium by a thermal sublimation transfer process; putting an image-forming object and a transfer sheet for an adhesive layer according to any one of the above transfer sheets, for an adhesive layer, on top of the other so as for the image-forming object to abut against the adhesive layer of the transfer sheet for an adhesive layer and applying heat and/or pressure to the laminate by transfer means to transfer the adhesive layer onto the image-forming object; putting the image-forming object and the intermediate transfer medium on top of the other for registration by taking advantage of the low tackiness of the adhesive layer present on the image-forming object; and transferring the image-receptive layer onto the image-forming object through the adhesive layer.
According to a yet further aspect of the present invention, there is provided an intermediate image-forming object, comprising an intermediate transfer medium having a releasable image-receptive layer; an image formed on the image-receptive layer by a thermal sublimation transfer process; and an adhesive layer having low tackiness provided on at least an image-formed area of the image-receptive layer. In a preferred embodiment of the present invention, the intermediate image-forming object further comprises an interposing layer between the image-receptive layer and the adhesive layer; or at least one of the adhesive layer and the interposing layer contains a filler.
According to a yet further aspect of the present invention, there is provided an intermediate image-forming object, comprising: an image-forming object; and an adhesive layer, having low tackiness, provided on a desired area of the image-forming object. In a preferred embodiment of the intermediate image-forming object according to the present invention, the intermediate image-forming object further comprises a peel layer on the adhesive layer, the glass transition point of the peel layer being above that of the adhesive layer.
According to a yet further aspect of the present invention, there is provided an object with an image formed thereon, comprising: an image-forming object; an adhesive layer provided on a desired area of the image-forming object; and an image-receptive layer provided on the adhesive layer, the image-receptive layer having an image formed by a thermal sublimation transfer process.
In a preferred embodiment of the object with an image formed thereon according to the present invention, the object with an image formed thereon further comprises an interposing layer between the image-receptive layer and the adhesive layer; or at least one of the adhesive layer and the interposing layer contains a filler.
According to another preferred embodiment of the object with an image formed thereon according to the present invention, the object with an image formed thereon further comprises a peel layer between the image-receptive layer and the adhesive layer, the glass transition point of the peel layer being above that of the adhesive layer.
Since the adhesive layer provided on the substrate sheet has low tackiness, the adhesive layer transferred onto the transfer material also has low tackiness. By virtue of the above construction, in the case of the transfer of the transfer material onto a different object through the adhesive layer, after the adhesive layer is once brought into contact with a different object, it can be released from and re-adhered to the object. Further, the interposing layer formed on the adhesive layer has good adhesion to a transfer material (for example, an intermediate transfer medium provided with an image-receptive layer), onto which an adhesive layer is to be transferred, and, at the same time, can function to prevent bleeding of dyes. Therefore, the transfer of the adhesive layer onto a transfer material is very good, and the peel layer formed between the substrate sheet and the adhesive layer is satisfactorily separated from the substrate sheet and located on the surface of the transferred adhesive layer, enabling good surface properties to be maintained even though the adhesive layer penetrates into an object (for example, an image-forming object such as paper). Thus, after the adhesive layer is transferred onto an intermediate transfer medium as a transfer material or an image-forming object, registration between the intermediate transfer object and the image-forming object can be easily performed by taking advantage of low tackiness of the adhesive layer.
Meaning of the above terms will be described. In the present invention, the term xe2x80x9cadhesive layerxe2x80x9d refers to a layer for imparting adhesion mainly to an image-forming object. Both the terms xe2x80x9cinterposing layerxe2x80x9d and xe2x80x9cpeel layerxe2x80x9d refer to a layer which functions as a second adhesive layer because both layers impart adhesion to the intermediate transfer medium. However, it should be noted that the xe2x80x9cinterposing layerxe2x80x9d on the transfer sheet for an adhesive layer, together with the xe2x80x9cadhesive layer,xe2x80x9d is transferred onto the receptive layer of the intermediate transfer medium. On the other hand, the xe2x80x9cpeel layer,xe2x80x9d together with the adhesive layer, is transferred onto the image-forming object before the receptive layer is transferred. Therefore, it should be noted that the xe2x80x9cinterposing layerxe2x80x9d and the xe2x80x9cpeel layerxe2x80x9d are different from each other in object onto which the layer is transferred. In this sense, these words each are used in its proper way.